From 00cebd6f22beb6d5fa65ed2d8d1ff9acf59bce61 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Thu, 28 Jun 2018 09:08:04 +0200 Subject: [PATCH] x86: guard against #NM Just in case we still don't get CR0.TS handling right, prevent a host crash by honoring exception fixups in do_device_not_available(). This would in particular cover emulator stubs raising #NM. Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper --- xen/arch/x86/traps.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c index 3e05cf172c..9f045a2045 100644 --- a/xen/arch/x86/traps.c +++ b/xen/arch/x86/traps.c @@ -1749,7 +1749,21 @@ void do_device_not_available(struct cpu_user_regs *regs) { struct vcpu *curr = current; - BUG_ON(!guest_mode(regs)); + if ( !guest_mode(regs) ) + { + unsigned long fixup = search_exception_table(regs); + + gprintk(XENLOG_ERR, "#NM: %p [%ps] -> %p\n", + _p(regs->rip), _p(regs->rip), _p(fixup)); + /* + * We shouldn't be able to reach here, but for release builds have + * the recovery logic in place nevertheless. + */ + ASSERT_UNREACHABLE(); + BUG_ON(!fixup); + regs->rip = fixup; + return; + } vcpu_restore_fpu_lazy(curr); -- 2.30.2